After several batches without significant issues, this long-term Korean wholesaler began seeing a sharp increase in motor failure complaints. End-consumers were reporting burnout within 5–10 minutes of startup — sparks visible, machines unrecoverable. Some units failed immediately on first power-on.

A portion of end-customers chose full refunds rather than repair, meaning the machines could not be resold. The client's market reputation was taking a measurable hit.

The client had already done their own analysis before escalating. Drawing on years of after-sales repair experience, they disassembled both failed and intact motors and found a structural difference: failed motors had no visible gap in the assembly; intact motors had a clear gap between components.

They provided two sets of photographs — motors from units that had not failed, and motors from all the damaged units — and put forward a specific hypothesis: the assembly gap was the variable. Their recommendation was to investigate the motor assembly process directly, not to run general QC checks. This level of diagnostic specificity from a distributor is not common, and it set the direction for everything that followed.

• 01 Solution validation. We did not treat the client's hypothesis as assumed correct. Our engineers assembled and ran motors in both configurations — gap vs. no gap — to confirm or refute the theory with our own test data before committing to any production change.
• 02 Motor production control. Testing confirmed the client's assessment. Fix: 1mm washer added to the assembly, producing approximately 2mm gap and 9–10mm shaft clearance. Because we produce motors in-house, this change was implemented directly on the production line. The entire revised assembly process was documented in video and photographs and sent to the client.
• 03 100+ hour durability test. Multiple fully assembled machines were run continuously under load conditions simulating real field use — tilling through soil and sand. No motor failures were recorded; thermal behaviour remained within normal range throughout.
• 04 Pre-production sample. A sample built to the revised specification was provided to the client for independent testing. Their approval was a prerequisite for the mass production run to proceed.
• 05 Mass production + full inspection. Every unit in the production run was subject to a run test before leaving the facility. No batch-sampling — 100% inspection before shipment.

Client testing of the pre-production sample confirmed the revised motor assembly performed to specification. Durability results accepted. Mass production proceeded on the basis of a confirmed fix, not an assumed one.

All rework and testing costs — including the 100-hour endurance test and full-unit inspection across the production run — were absorbed on our side. The client was not asked to contribute to the cost of fixing a problem that originated in our production process.

The client has continued placing repeat orders since this case was resolved. In follow-up correspondence, they noted that what gave them confidence to continue was the way the issue was handled: feedback was received without defensiveness, each point was addressed with evidence rather than reassurance, and workable solutions were delivered for every item raised.

Following this case, the client requested a revision to the inspection protocol for their orders. The new standard has been implemented and applies as the default for all batches going forward.